Re: drm/amdgpu: implement cgs gpu memory callbacks

On Tue, Aug 25, 2015 at 02:07:21AM +0000, Zhou, David(ChunMing) wrote:

...

and can the shift actually wrap?

[DZ] of course, adding shift wrap is better. fpfn/lpfn is page number, so <<PAGE_SHIFT is to convert to memory size.

By "Shift wrap" I meant how you shift beyond the end of a 32bit number and it truncates, or if it's signed then it can wrap around (it's undefined actually, I probably should use a different word?).

int main(void) { unsigned long long a = 0xf0000000U << 12; unsigned long long b = 0xf0000000ULL << 12;

printf("%llx %llx\n", a, b);

return 0; }

regards, dan carpenter